/*
 * [New BSD License]
 * Copyright (c) 2011-2012, Brackit Project Team <info@brackit.org>  
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Brackit Project Team nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.brackit.xquery.util.sort;

import java.util.Comparator;

import org.brackit.xquery.ErrorCode;
import org.brackit.xquery.QueryContext;
import org.brackit.xquery.QueryException;
import org.brackit.xquery.Tuple;
import org.brackit.xquery.atomic.Atomic;
import org.brackit.xquery.expr.Cast;
import org.brackit.xquery.node.stream.TransformerStream;
import org.brackit.xquery.xdm.DocumentException;
import org.brackit.xquery.xdm.Expr;
import org.brackit.xquery.xdm.Item;
import org.brackit.xquery.xdm.Sequence;
import org.brackit.xquery.xdm.Stream;
import org.brackit.xquery.xdm.Type;

/**
 * @author Sebastian Baechle
 * 
 */
public class Ordering implements Comparator<Tuple> {

	final Expr[] orderByExprs;
	final OrderModifier[] modifier;
	int offset;
	TupleSort sort;

	public Ordering(Expr[] orderByExprs, OrderModifier[] modifier) {
		this.orderByExprs = orderByExprs;
		this.modifier = modifier;
	}

	public void add(QueryContext ctx, Tuple t) throws QueryException {
		if (sort == null) {
			offset = t.getSize();
			sort = new TupleSort(this, 1);
		}
		sort.add(t.concat(sortKeys(ctx, t)));
	}

	public void add(Sequence[] keys, Tuple t) throws QueryException {
		if (sort == null) {
			offset = t.getSize();
			sort = new TupleSort(this, 1);
		}
		sort.add(t.concat(keys));
	}

	public Stream<Tuple> sorted() throws QueryException {
		sort.sort();
		Stream<Tuple> s = new TransformerStream<Tuple, Tuple>(sort.stream()) {
			@Override
			protected Tuple transform(Tuple next) throws DocumentException {
				try {
					return next.project(0, offset);
				} catch (QueryException e) {
					throw new DocumentException(e);
				}
			}
		};
		sort = null;
		return s;
	}

	public Sequence[] sortKeys(QueryContext ctx, Tuple t) throws QueryException {
		Sequence[] concat = new Sequence[orderByExprs.length];
		for (int i = 0; i < orderByExprs.length; i++) {
			Item item = orderByExprs[i].evaluateToItem(ctx, t);
			Atomic atomic = (item != null) ? item.atomize() : null;
			if ((atomic != null) && (atomic.type().instanceOf(Type.UNA))) {
				atomic = Cast.cast(null, atomic, Type.STR);
			}
			concat[i] = atomic;
		}
		return concat;
	}

	public static class OrderModifier {
		public OrderModifier(boolean asc, boolean emptyLeast, String collation) {
			this.ASC = asc;
			this.EMPTY_LEAST = emptyLeast;
			this.collation = collation;
		}

		public final boolean ASC;
		public final boolean EMPTY_LEAST;
		public final String collation;
	}

	@Override
	public int compare(Tuple o1, Tuple o2) {
		try {
			for (int i = 0; i < modifier.length; i++) {
				int pos = offset + i;
				Atomic lAtomic = (Atomic) o1.get(pos);
				Atomic rAtomic = (Atomic) o2.get(pos);

				if (lAtomic == null) {
					if (rAtomic != null) {
						return (modifier[i].EMPTY_LEAST) ? -1 : 1;
					}
				}
				if (rAtomic == null) {
					return (modifier[i].EMPTY_LEAST) ? 1 : -1;
				}

				int res = lAtomic.cmp(rAtomic);
				if (res != 0) {
					return (modifier[i].ASC) ? res : -res;
				}
			}
			return 0;
		} catch (QueryException e) {
			if (e.getCode() == ErrorCode.ERR_TYPE_INAPPROPRIATE_TYPE) {
				throw new ClassCastException(e.getMessage());
			} else {
				throw new RuntimeException(e);
			}
		}
	}

	public void clear() {
		if (sort != null) {
			sort.clear();
			sort = null;
		}
	}
}
